This document provides a sample configuration using IPv6 that helps you to configure BGP Prefix-Based Outbound Route Filtering. This feature uses BGP outbound route filter (ORF) send and receive capabilities that minimize the number of BGP updates sent between peer routers. The configuration of this feature can help in filtering out unwanted routing updates at the source.
Make sure that you meet these requirements before you attempt this configuration:
Have an understanding of BGP routing protocol and its operation
Have an understanding of the IPv6 Addressing scheme
This document is not restricted to specific software and hardware versions.
The configurations in this document are based on the Cisco 7200 Series Router with Cisco IOS® Software Release 15.0(1).
Refer to Cisco Technical Tips Conventions for more information on document conventions.
In this example, router R1 is configured to advertise-prefix based ORF send capabilities to router R2. On the other end router R2 is configured to advertise the prefix-based ORF receive capabilities to router R1. Before the BGP Prefix-Based Outbound Route Filtering feature can be enabled to send or receive prefix-based ORF announcements, BGP peering sessions must be up and running and BGP ORF capabilities must be enabled on each participating router before a router.
This document uses the neighbor orf prefix-filter command in order to enable the ORF prefix list capability on the router. This command was introduced in Cisco IOS Software Release 12.0(11)ST.
Note: Use the Command Lookup Tool (registered customers only) in order to find more information on the commands used in this document.
This document uses this network setup:
This document uses these configurations:
Router R1 |
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! hostname R1 ! ipv6 unicast-routing ipv6 cef ! ! interface Loopback1 no ip address ipv6 address 1111::1/128 ! ! interface Loopback2 no ip address ipv6 address 2222::1/128 ! ! interface Serial1/0 no ip address ipv6 address 2011:11:11:11::1/64 serial restart-delay 0 ! ! router bgp 6501 no synchronization no bgp default ipv4-unicast bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 capability orf prefix-list send neighbor 2011:11:11:11::2 prefix-list FILTER_IPv6 in exit-address-family ! ! ipv6 prefix-list FILTER_IPv6 seq 10 permit 1111::1/128 ipv6 prefix-list FILTER_IPv6 seq 20 permit 2222::1/128 ! ! end |
Router R2 |
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! hostname R2 ! ! no ip domain lookup ipv6 unicast-routing ipv6 cef ! interface Loopback1 no ip address ipv6 address 1010::1/128 ! ! interface Loopback2 no ip address ipv6 address 2020::1/128 ! interface Serial1/0 no ip address ipv6 address 2011:11:11:11::2/64 serial restart-delay 0 ! ! router bgp 6502 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 2011:11:11:11::1 remote-as 6501 neighbor 2011:11:11:11::1 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1010::1/128 network 2020::1/128 neighbor 2011:11:11:11::1 activate neighbor 2011:11:11:11::1 capability orf prefix-list receive neighbor 2011:11:11:11::1 prefix-list R2_list in exit-address-family ! ipv6 prefix-list R2_list seq 10 permit 1010::1/128 ipv6 prefix-list R2_list seq 20 permit 2020::1/128 ! end |
In this scenario, a loopback address 1000::1/45 is configured in R1 under interface loopback 0 . A prefix-list is created in order to allow any routes that are greater than prefix-length ::/64.
Note: The configuration of router R2 remains the same as previously given and R1 configuration changes as shown here. The IP addresses on these routers remains the same.
Router R1 |
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!--- Output omitted. ! interface Loopback0 no ip address ipv6 address 1000::1/45 ! !--- Output omitted. router bgp 6501 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1000::1/45 network 1111::1/128 network 2222::1/128 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 prefix-list IPV6-LONG in !--- Applies the prefix-list and filters !--- the incoming updates from the neighbor 2011:11:11:11::2. exit-address-family ! ipv6 prefix-list IPV6-LONG description Match any prefix longer than /64 ipv6 prefix-list IPV6-LONG seq 1 permit ::/0 ge 64 !--- seq 1 permit ::/0 ge 64 permits anything !--- that is ge /64 subnet mask. ! end |
Use this section to confirm that your configuration works properly.
The Output Interpreter Tool (registered customers only) (OIT) supports certain show commands. Use the OIT to view an analysis of show command output.
These show commands are used to verify the configuration:
show running-config | beg bgp
In Router R1:
show running-config | beg bgp |
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router bgp 6501 no synchronization bgp router-id 1.1.1.1 bgp log-neighbor-changes neighbor 2011:11:11:11::2 remote-as 6502 neighbor 2011:11:11:11::2 ebgp-multihop 255 no auto-summary ! address-family ipv6 neighbor 2011:11:11:11::2 activate neighbor 2011:11:11:11::2 capability orf prefix-list send !--- Indicates that the neighbor 2011:11:11:11::2 !--- is configured with the prefix-based !--- ORF feature in send mode. |
show bgp ipv6 unicast neighbors |
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R1#show bgp ipv6 unicast neighbors 2011:11:11:11::2 BGP neighbor is 2011:11:11:11::2, remote AS 6502, external link BGP version 4, remote router ID 2.2.2.2 Session state = Established, up for 01:30:36 Last read 00:00:44, last write 00:00:42, hold time is 180, keepalive interval is 60 seconds BGP multisession with 2 sessions (2 established), first up for 01:31:26 Neighbor sessions: 2 active, is multisession capable Neighbor capabilities: Route refresh: advertised and received(new) on session 1, 2 Four-octets ASN Capability: advertised and received on session 1, 2 Address family IPv4 Unicast: advertised and received Address family IPv6 Unicast: advertised and received !--- Output omitted. For address family: IPv6 Unicast Session: 2011:11:11:11::2 session 2 BGP table version 1, neighbor version 1/0 Output queue size : 0 Index 2 session 2 member 2 update-group member AF-dependant capabilities: Outbound Route Filter (ORF) type (128) Prefix-list: !--- Shows that the neighbor 2011:11:11:11::2 !--- is configured with the prefix-based !--- ORF feature in send mode. Send-mode: advertised Receive-mode: received Outbound Route Filter (ORF): sent; Incoming update prefix filter list is FILTER_IPv6 Sent Rcvd Prefix activity: ---- ---- Prefixes Current: 2 4 Prefixes Total: 0 0 Implicit Withdraw: 1 0 Explicit Withdraw: 1 0 Used as bestpath: n/a 0 Used as multipath: n/a 0 Outbound Inbound Local Policy Denied Prefixes: -------- ------- !--- Output omitted. |
In Router R2:
show running-config | beg bgp |
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router bgp 6502 no synchronization bgp router-id 2.2.2.2 bgp log-neighbor-changes neighbor 2011:11:11:11::1 remote-as 6501 neighbor 2011:11:11:11::1 ebgp-multihop 255 no auto-summary ! address-family ipv6 network 1010::1/128 network 2020::1/128 neighbor 2011:11:11:11::1 activate neighbor 2011:11:11:11::1 capability orf prefix-list receive !--- Indicates that the neighbor 2011:11:11:11::1 !--- is configured with the prefix-based !--- ORF feature in receive mode. |
show bgp ipv6 unicast neighbors |
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R2#show bgp ipv6 unicast nei 2011:11:11:11::1 BGP neighbor is 2011:11:11:11::1, remote AS 6501, external link BGP version 4, remote router ID 1.1.1.1 Session state = Established, up for 01:47:11 Last read 00:00:44, last write 00:00:32, hold time is 180, keepalive interval is 60 seconds multisession with 2 sessions (2 established), first up for 01:48:02 Neighbor sessions: 2 active, is multisession capable Neighbor capabilities: Route refresh: advertised and received(new) on session 1, 2 Four-octets ASN Capability: advertised and received on session 1, 2 Address family IPv4 Unicast: advertised and received Address family IPv6 Unicast: advertised and received Multisession Capability: advertised and received !--- Output omitted. For address family: IPv6 Unicast Session: 2011:11:11:11::1 session 2 BGP table version 3, neighbor version 3/0 Output queue size : 0 Index 3 session 2 member 3 update-group member AF-dependant capabilities: Outbound Route Filter (ORF) type (128) Prefix-list: !--- Shows that the neighbor 2011:11:11:11::1 !--- is configured with the prefix-based !--- ORF feature in receive mode. Send-mode: received Receive-mode: advertised Outbound Route Filter (ORF): received (2 entries) Incoming update prefix filter list is R2_list Sent Rcvd Prefix activity: ---- ---- Prefixes Current: 2 5 Prefixes Total: 0 0 Implicit Withdraw: 0 0 Explicit Withdraw: 2 0 !--- Output omitted. |
Issue the show ipv6 route bgp command in router R1 in order to display the current contents of the IPv6 BGP routing table.
show ipv6 route bgp |
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In router R1: R1#show ipv6 route bgp IPv6 Routing Table - default - 9 entries Codes: C - Connected, L - Local, S - Static, U - Per-user Static route B - BGP, HA - Home Agent, MR - Mobile Router, R - RIP I1 - ISIS L1, I2 - ISIS L2, IA - ISIS interarea, IS - ISIS summary D - EIGRP, EX - EIGRP external, ND - Neighbor Discovery O - OSPF Intra, OI - OSPF Inter, OE1 - OSPF ext 1, OE2 - OSPF ext 2 ON1 - OSPF NSSA ext 1, ON2 - OSPF NSSA ext 2 B 1010::1/128 [20/0] via 2011:11:11:11::2 B 2020::1/128 [20/0] via 2011:11:11:11::2 !--- In this ouput, 1000::1/45 is not !--- displayed because the network is lesser !--- than ::/64 prefix and its filtered. |
Use the show ipv6 prefix-list command in order to display information about an IPv6 prefix list or IPv6 prefix list entries.
show ipv6 prefix-list |
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In router R1: R1#show ipv6 prefix-list detail Prefix-list with the last deletion/insertion: IPV6-LONG ipv6 prefix-list IPV6-LONG: Description: Match any prefix longer than /64 count: 1, range entries: 1, sequences: 1 - 1, refcount: 3 seq 1 permit ::/0 ge 64 (hit count: 14, refcount: 1) R1#show ipv6 prefix-list summary Prefix-list with the last deletion/insertion: IPV6-LONG ipv6 prefix-list IPV6-LONG: Description: Match any prefix longer than /64 count: 1, range entries: 1, sequences: 1 - 1, refcount: 3 R1#show ipv6 prefix-list IPV6-LONG ipv6 prefix-list IPV6-LONG: 1 entries seq 1 permit ::/0 ge 64 |
Revision | Publish Date | Comments |
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1.0 |
14-Jun-2012 |
Initial Release |